湖南川口印支期花岗岩成因及与钨成矿关系  

Petrogenesis of the Late Triassic Chuankou Granite and Implications for Tungsten Mineralization,Hunan Province

作　　者：罗鹏 陈迪 杨俊 凌跃新 罗来 LUO Peng;CHEN Di;YANG Jun;LING Yue-Xin;LUO Lai(Hunan Institute of Geology Survey,Changsha 410116,Hunan,China)

机构地区：[1]湖南省地质调查院,湖南长沙410116

出　　处：《华南地质》2021年第3期247-264,共18页South China Geology

基　　金：湖南省自然科学基金项目(青年基金)(项目编号:2018JJ3269)。

摘　　要：川口花岗岩体位于南岭成矿带北西侧,赋存有大型川口钨矿床。川口花岗岩主要由二长花岗岩和白云母花岗岩组成,具有高硅、富碱的特点,属高钾钙碱性系列,为分异的S型花岗岩。SHRIMP锆石U-Pb同位素测年与辉钼矿Re-Os同位素测年表明,川口花岗岩体中细粒含斑二云母二长花岗岩成岩年龄为223.1±2.6 Ma,成矿年龄为225.8±1.2 Ma,表明其成岩成矿时代为印支期。元素地球化学及Sr、Nd同位素特征表明:川口花岗岩来源于古元古代泥质岩的部分熔融,形成于印支期陆内伸展-减薄的构造环境。川口花岗岩与钨矿床在时空上高度吻合,钨矿与花岗岩的Y/Ho比值相近,且两者在Y-Ho图解上显示出良好的线性关系,结合钨矿石中Re同位素和流体包裹体氧同位素组成特征,认为川口花岗岩岩浆经历了高度分离结晶,产生了富挥发分的成矿流体而形成钨矿。作为华南地区印支期花岗岩成岩成矿事件的典型实例,川口花岗岩与川口钨矿指示了华南地区印支期花岗岩具备较大的钨矿成矿潜力。The Chuankou granite is located on the northwest side of the Nanling Metallogenic Belt and hosts the large Chuankou tungsten deposit.The Chuankou pluton is mainly composed of monzonitic granite and muscovite granite and belongs to high-Si,rich alkali differentiated S-type granite of high-K calc-alkaline se-ries.SHRIMP zircon U-Pb isotopic age of fine-grained porphyry monzonitic granite is 223.1±2.6 Ma,and its molybdenite Re-Os isotopic age is 225.8±1.2 Ma,which proves that the Chuankou granite and tungsten de-posit were formed in Late Triassic(Indosinian).The elemental and Sr-Nd isotopic geochemistries indicate that the Chuankou granite was originated from the partial melting of the Paleoproterozoic argillaceous rock and formed in the Indosinian intracontinental extension-thinning setting.The Chuankou granite has closed spa-tial-temporal relation with the tungsten deposit,and the two show good linear relationship on Y-Ho diagram.The similarity in Y/Ho ratio and the oxygen isotope characteristics of fluid inclusion indicate that the magma of Chuankou granite has undergone a high degree of separation and crystallization,and produced volatile-rich ore-forming fluids to form tungsten ore.As a typical example of the diagenesis and mineralization event of Indosinian granites in South China,the Chuankou granite and tungsten deposit indicate that the Indosinian granites in South China have great tungsten mineralization potential.

关 键 词：SHRIMP锆石U-PB测年 RE-OS同位素测年 印支期成矿 川口花岗岩 湖南 

分 类 号：P581[天文地球—岩石学] P618.67[天文地球—地质学]